Campylobacter Bacteriophage Cocktail Design Based on an Advanced Selection Scheme.

Severin Michael Steffan,Manfred Rohde,Corinna Kehrenberg,Elisa Peh,Madeleine Plötz,Sophie Kittler,Golshan Shakeri

doi:10.3390/antibiotics11020228

Abstract

Campylobacteriosis is a worldwide-occurring disease and has been the most commonly reported zoonotic gastrointestinal infection in the European Union in recent years. The development of successful phage-based intervention strategies will require a better understanding of phage–bacteria interactions to facilitate advances in phage cocktail design. Therefore, this study aimed to investigate the effects of newly isolated group II and group III phages and their combinations on current Campylobacter field strains. A continuous workflow for host range and efficiency of plating (EOP) value determination was combined with a qPCR-based phage group identification and a liquid-based planktonic killing assay (PKA). An advanced analysis scheme allowed us to evaluate phage cocktails by their efficacy in inhibiting bacterial population growth and the resulting phage concentrations. The results of this study indicate that data obtained from PKAs are more accurate than host range data based on plaque formation (EOP). Planktonic killing assays with Campylobacter appear to be a useful tool for a straightforward cocktail design. Results show that a group II phage vB_CcM-LmqsCP218-2c2 and group III phage vB_CjM-LmqsCP1-1 mixture would be most promising for practical applications against Campylobacter coli and Campylobacter jejuni.

Highlights

Campylobacter enteritis is a widespread infectious disease in humans worldwide, most often associated with the species Campylobacter (C.) coli and jejuni [1,2]
High meanc24 values indicated that CP218-2c2 virions could replicate in LH83 and Cc4 cells, while the same appeared to be true for CP1-1 in Cj18. Results from this and previous studies [14,17,18,32] indicate that the formulation of phage cocktails in general could profit from an increased use of advanced selection schemes incorporating methods such as planktonic killing assays (PKAs), which could be combined with standardized analysis methods
This study describes a continuous workflow for host range and efficiency of plating (EOP) value determination [32] in combination with a qPCR-based phage group identification [36] and a PKA assay that allowed us to evaluate phage cocktails with an advanced analysis scheme partially based on the virulence index proposed by Zachary et al

Summary

Introduction

Campylobacter enteritis (campylobacteriosis) is a widespread infectious disease in humans worldwide, most often associated with the species Campylobacter (C.) coli and jejuni [1,2]. The European Food Safety Authority (EFSA) started issuing annual summary reports on the trends and sources of zoonoses in 2005. C. jejuni and C. coli are commensals occurring in the intestines of various wild, domestic, and farm animals [1,5]. The pathogens can contaminate animal carcasses, while later contamination of other foodstuffs by cross-contamination is possible during food preparation [6,7,8,9]. The minimum infectious dose for Campylobacter sp. If Campylobacter loads in chicken ceca could be reduced by 102 CFU, current models by EFSA predict a 42%

Objectives

Methods

Results

Discussion

Conclusion